Method of treating ores.



L. C. DREFAHL.

METHOD OF TREATING ORES.

APPLICATION FILED APR. 15, 1914.

Pafentedfiept. 14, 1915.

HTTOE/VEYoS- WW i403. 1mg

* 1 r s an ore.

LOUIS C. DREFAHL, 0F CLEVELAND, OHIO,

ASSIGNOR TO THE GRASSELLI CHEMICAL COMPANY, OF CLEVELAND, OHIO, A CQRPORATIQN OF OHIO.

maaeoa.

METHOD 01E TREATING} GEES.

Specification of Letters Eatent. Patcgntegol Staph 14L, 1915,

Application filed April 15, 1914. Serial No. 832,079.

To all whom it may concerh:

Be it known that I, LoUIs C. DREFAHL, a citizen of the United States, and a resident of Cleveland, county of Cuyahoga, and State of Ohio, have invented a new and useful Improvement in Methods of Treating Ores, of which the following is a specification, the principle of the invention being herein explained and the best mode in which I have contemplated applying that principle, so as to distinguish it from other inventions.

By reason of the use of modern and improved separating, concentrating and metal lurgical processes, such for example as the so-called flotation process, ores and concentrates, particularly those containing zinc, lead, copper, silver, gold and other metals, and metalliferous materials of the same general physical condition, are being produced in an extremely fine and dusty condition.

The desulfurization, ,calcination or oxidation of these ores, ore concentrates, and metalliferous materials of the same general physical condition, preliminary to further metallurgical treatment, is difficult and inconvenient for the reason that ..unusually high losses'are entailed in treating materials of this character in any type of furnace or other apparatus at the present time available for the purpose. In addition to the loss of material thus incurred, the handling of such products is inconvenient. I

The object of the present improved process and apparatus, accordingly, is to put ores and ore concentrates of the kind in question, and particularly zinc and silver sulfids, into a form or condition in which they. can be handled without the losses referred to above and without attendant inconveniences to the operatives, while at the same time the processof desulfurizing, calcination, or thelike, may be carried on with thoroughness and despatch in furnaces of the type at present in use.

To the accomplishment of the foregoing and related objects, said invention, then,consists of the steps and means hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following description set forth in detail certain means and one mode of carrying out the invention, such disclosed means and mode illustrating, however, but one of various ways in which the be used.

In said annexed drawing: Figure 1 is a longitudinal sectional-view of an apparatus adapted for carrying out my improved process, such apparatus being illustrated more or less diagrammatically; and Fig. 2 is an end elevational view of one part of such apparatus.

It will be understood that as received, the fine powder composing the ore or ore concentrates will often contain a certain per centage of moisture, the amount of the latter being usually sufficient to give the'same the consistency of a plastic mass. Before desulfurizing, calcining, oxidizing, even if not dried, the operations of desulfurizing, calcining, oxidizing, or smelting, will raise the material to such temperature so as to dry same, in which case the mass takes the form of a dry powder, which it is the object of the present process to avoid.

According to the present process, I mix the ore, or ore concentrates, or metalliferous materials of the same general physical condition, containing sufficient water to render the same plastic, as above stated, which serves to hold the fine particles of the powder together. I then condition the mass, that is, render the same of well defined granular or lumpy form, to make it possible to subsequently desulfurize, calcine, or otherwise treat the same with decreased losses in furnaces or other apparatus, and fit it for subsequent metallurgical operations. In some cases the operation may be facilitated by the addition of a suitable binder. It is quite important that the size of such particles be not too large, or otherwise the materials will not respond properly to desulfurization, calcination, oxidation, or smelting. For example, in the case of the particular ore'mentioned above, namely zinc and silver sulfids, the size of the granules or nodules, as I shall for convenience term them, should be in the neighborhood of that of ordinary beans.

As one specific way of carrying out my principle of the invention may process, I thoroughly mix with the moisbinder such as sulfate of iron, that is crystallized ferrous sulfate in the particular case in hand. The foregoing mixture is then introduced into a pug mill or similar mechanism 1, where the ingredients are thoroughly worked together by a rotating screw 2 or the like, and finally, expressed through a perforated plate 3 in the form of a number of tiny streams having the diameter of a lead pencil, or thereabout. These streams of material naturally tendto break up into short fragments, but this is assisted by causing them to fall onto a vertically reciprocating pan 4, which combines the function of a chute by guiding the material onto an endless belt conveyer 5, as will be presently described. Such pan -1 is pivotally attached at its upper end 6 to the casing of the mill and the spindle 7 of the latter carries at its rear end a disk 8 having two projecting pins 9 that are adapted to successively strike a transverse bar 10 attached to the pan and thereby depress the same againsta tension-spring 11, the result being to oscillate the pan rapidly and at the same time jar the material as the pins successively strike the bar. A transversely oscillatory arm 12 depends in front of the perforated plate 8, being hung at its upper end on a 'pin and actuated by an eccentric 14 on the same Spindle that carries the disk. The result of the oscillation of this arm is to distribute the material equally across the pan as it is discharged through the aper-' tures in the plate.

The upper portion of the endless conveyer belt 5, which moves in the direction indicated by the arrows in Fig. 1, passes through a long furnace chamber 15, preferably of tubular form, entirely surroundingsuch belt conveyer. Into the farther end of this furnace chamber a gas burner 16 located above the belt discharges so as to cause a current of heated gases to pass through the chamber in the reverse direction to that in which the belt with the material thereon is moving; while a series of small'burners 17 are disposed beneath the belt so as to heat the latter, the gases from all the foregoing burners escaping by way of a flue 18 at the end of the furnace nearest to the mixing mill.

The length of the furnace and the location and extent of the heating agencies just re ferred to, are designed to be such that the mass of granules or nodules received from the mill onto the conveyer belt becomes thoroughly dried by the time it is discharged from such belt at the farther end of the furnace. The formed, material thus discharged, will stand ordinary shoveling without much further breaking up. Such formed material.- in other words, can be carried to the desulfurizing, calcining or oxidizing furnace or other suitable apparatus, and

factory desulfurization, calcination, oxidathere treated with less loss than by the use of methods heretofore employed. At the same time, the size of the formed material, being as above stated, permits of the satistion or further metallurgical treatment of the same.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the steps or mechanism herein disclosed. provided the steps stated by any of the following claims or the equivalent of such stated steps be employed.

I therefore particularly point out and distinctly claim as my invention 2-- 1. The method of conditioning fine or dusty ore material for further treatment, which consists in forming such material into a plastic mass; dividing up such mass into relatively small nodules; and then maintaining such nodules relatively stationary and simultaneously subjecting the same to heat suflicient to dry and harden, but not otherwise affect the same.

2. The method of conditioning fine or dusty ore material for further treatment,

sists in moistening such material and intermixing a suitable binder, so as to form 1 thereof a plastic mass; dividing up such mass into small nodules; and then maintaining such nodules relatively stationary and simultaneously subjecting the same to heat sufiicient to expel the moisture therefrom 1 and set such binder, but not otherwise affect said nodules.

l. The method of conditioning fine or dusty ore material for treatment, which consists in moistening such material and intermixing a suitable binder, so as to form thereof a plastic mass; expressing such mass through perforations in the form of small streams; breaking up such streams into relatively small fragments or nodules; and then maintaining such nodules relatively stationary and simultaneously subjecting the same to heat suflicient to expel the moisture therefrom and set such binder, but not otherwise affect said nodules.

5. The method of preparing finely pulverized zinc and silver sulfid ores for desulfurization, which consists in moistening such ores and intermixing a suitable binder so as to form thereof a plastic mass; divid- I ing up such mass into small nodules; and then maintaining such nodules relatively stationary and simultaneously subjecting the same to heat sufiicient to expel the moisture therefrom and set such binder, but not otherwise affect such nodules.

6. The method of preparing finely pulverized zinc and silver sulfid ores for desulfurization, which consists in moistening such ores and intermixing a small quantity of sulfate of iron as a binding material, so as to form a plastic mass; expressing such mass through a perforated plate in the form of small streams; breaking up such streams into relatively small fragments or nodules; and then maintaining such nodules relatively stationary and simultaneously subjecting the same to heat sufiicient to expel the moisture therefrom and set such binding material, but not otherwise aflect such 20 nodules.

Signed by me this 13th day of April, 1914.

I LOUIS C. DREFAHL. Attested by E. N. BAILEY, H; P. MANSFIELD. 

